The invention relates to a test device for testing electronic components mounted on a carrier such as a lead frame or substrate. The invention also relates to a test assembly of which at least one such test device forms part. In addition, the invention provides a method for testing electronic components mounted on a carrier such as a lead frame and a method for calibrating a test device.
The testing of electronic components, particularly semiconductors, usually takes place according to the prior art after a plurality of electronic components have been placed on a carrier. The carrier is subsequently subdivided into segments on which one component is situated in each case. The separate carrier segments with electronic components mounted thereon are individually placed for testing against for instance a test contact with which the measurement is performed.
The present invention has for its object to provide an improved test device and method for testing electronic components with which testing can take place in accurate manner at relatively high speed.
The invention provides for this purpose a test device. In a preferred embodiment the transport path for supplying a carrier connects onto the transport path for discharging a carrier. In another preferred embodiment the transport path for supplying a carrier runs at least partly parallel to at least a part of the transport path for discharging a carrier. Using this test device a whole carrier with a plurality of electronic components mounted thereon can be engaged in one operation. The engaged carrier and/or the electronic components mounted thereon can now be placed into contact, once or a number of times at different positions, with one or more test contacts. A significant advantage of the device according to the invention is that the time required for testing an electronic component can be considerably reduced. Fewer separate objects are carried into the test device. Another advantage of the test device according to the invention is that the accuracy of positioning of the component relative to the contacts increases so that the quality of contact improves and becomes more constant. The carrier does after all contain the original reference points (also designated as index holes) on the basis of which previous operations have taken place. When the electronic components are separated for the test device, use must be made for later positioning of derived reference points such as for instance a moulded housing. It will be apparent that use of the original reference points on the carrier enables a more precise positioning of the objects for testing. The accuracy of the measurement will hereby increase, whereby fewer products are unnecessarily rejected as a result. Yet another advantage of the test device according to the invention is that it enables testing relatively early in the production process, so that relatively quicker feedback is possible when errors are detected and whereby possibly expensive further operations can be dispensed with. Because a carrier for testing is taken from a supply path and a tested carrier is placed in a discharge path, a plurality of testing devices can be deployed parallel to each other for testing a production flow of carriers. The capacity of the testing device does not therefore need to form a bottle-neck in a production process. The supply and discharge of carriers can take place via a single transport path, in which case it is advisable to record which carriers have been tested and which have not been tested, but it is also possible to use different transport paths for supply and discharge of carriers. In this latter situation there is less necessity for monitoring which carriers have been tested since the presence in the discharge path already indicates that a carrier has been tested. It is however possible in both variants to deploy test devices parallel to each other.
In a preferred embodiment at least one transport path is adapted for transport in two directions. The flexibility of the test device is hereby further increased, particularly in respect of the arrangement in which it is used.
The manipulator is preferably provided with two substantially mutually perpendicular linear guides for displacing the manipulator in a plane. The manipulator can herein also be provided with a third linear guide which lies substantially perpendicular to the other two linear guides. Such a manipulator enables a precise positioning of the carrier relative to the test contact. It is also possible to use such a manipulator for placing carrier and test contact into mutual contact a number of times, for instance at different locations on the carrier. A precise positioning of carrier relative to test contact is then also possible. An advantage already described above is the short transporting time required between two measurement on the same carrier. Yet another advantage of the manipulator with linear guiding is that it is relatively inexpensive to manufacture and is easily maintained.
In yet another preferred embodiment, the test device is provided with identification means for identification of an individual carrier. The test results of determined positions on the carrier can thus be linked to the individual carrier so that in optional further processing of a carrier the test results can be taken into account.
In yet another preferred embodiment, the manipulator is provided with positioning means for positioning the carrier relative to the manipulator. Using the positioning means the manipulator can be positioned on the carrier relative to the original reference points.
For processing of the test data the test device preferably comprises a computer system which is connected to the test contact. In practice such a computer system is a number of times more expensive (for instance by a factor 4) than the test device itself. The productivity increase of the test device according to the invention compared to the prior art also entails that the productivity of the relatively expensive computer system also increases. Reduction of the processing time per measurement thus provides an advantage which extends beyond more optimal utilization of the test device without peripheral equipment.
The invention also provides a test assembly for testing electronic components mounted on a carrier such as a lead frame. Such a test assembly can operate as stand-alone unit but can also be built into a production line. In addition, one or more test devices can be incorporated in the test assembly as required.
The invention moreover provides a method for testing components mounted on a carrier such as a lead frame. A carrier can herein be tested during step C) by placing it in contact with a test contact. It is also possible for a carrier and/or components mounted on a carrier to be tested a number of times by placing these in contact with the test contact at a plurality of positions. It is also further possible to test the carrier and/or components mounted on a carrier a number of times by placing them in contact with a plurality of test contacts. This can take place simultaneously as well as successively. By taking a whole carrier with electronic components mounted thereon out of a transport path the advantages are obtained as already described above with reference to the device according to the invention. The relatively simple method enables it to be performed with a relatively simple device. Measurements can be performed at relatively high temperatures (100-200xc2x0 C.) but it is also possible to perform the method at relatively low temperatures (xe2x88x9260-xe2x88x9220xc2x0 C.). The device according to the invention can be used for cold as well as hot test conditions.
Depending on the conditions in which the test is carried out, the carrier can be taken before testing out of the same transport path as, or out of a different transport path from the one in which it is placed after testing. In a stand-alone application of the method, a single transport path may for instance suffice but in a situation where the method is performed simultaneously at different positions a multiple transport path is preferred.